Photographic developers



surface.

Patented Sept. 25, 1945 PHOTOGRAPH! DEVELOPERS Verne ll. Reckmeyer, Binghamton, N. Y., assignor to General Aniline & Film Corporation, NewYork, N. Y., a corporation of Delaware No Drawing. Application May 19,1942.

Serial No. 443,559

4C'iaims.

This invention pertains to a photographic de-" veloper, and moreparticularly to a. developer which has greatly improved characteristicsof speed and fineness of grain.

Many so-called flne grain developers have been proposed from time totime in thepast, but none of these prior developers is entirelysatisfactory. In all of these previous proposals, improved fineness ofgrain is achieved only at the cost of a considerable loss in effectivethreshold speed. Attempts have been made to avoid this speed loss by theuse of various alkalies in the developer. The use of the customaryalkalies, such as borax, sodium metaborate, trisodium phosphate,triethanol amine and the like, however, has always resulted in aconsiderable coarsening of the grain. Thus the desirable line graincharacteristics were lost.

With these defects of the prior art in view, it is accordingly oneobject of the present invention to provide a new and improved fine graindeveloper.

A further object is to provide a line grain developer which will retainthreshold speed without impairment of the line grain characteristics.

Still another object is to provide a dee working fine grain developerwhich will maintain maximum speed with a minimum of graininess.

Other objects and advantages will be apparent from the followingdescription.

It is known that in the use of ordinary developers in connection withphotographic gelatino silver halide emulsions, the main developmenttakes place nearest to the surface of the exposed layer. In other words,the chief density is due to the presence of developed silver particlesnear this These silver particles form grain clusters, and it is apparentthat the presence of these grain clusters in a relatively thin layernear the surface of the emulsion will give rise to a graininess effectdue to passage of light between the grains. I

To avoid the above dimculties, certain developers have been used whichachieve the same given density by a more uniform distribution of silverthroughout the light sensitive layer. These are the so-calleddeepworking developers, of which They show oped silver particles aremore evenly distributed by reason of the characteristic solvent actionof the developing compound. Thus. even though the graininesscharacteristics are improved, the developer is unsatisfactory from apractical standpoint due to the effective loss in speed, which maycorrespond to diilerences of from 1 to 1% lens stops in a particularcase.

We have now found that the above stated objects canbe accomplished bythe use of 9. developing agent to give uniform distribution of thedeveloped silver particles energised with an easily oxldizable organiccompound, which, when oxidized, tends to set free a limited amount ofalkali. Preferably easily oxidizable alkali metal salts of organiccompounds of the phenolic type are employed for this purpose. Thus, thephenolates are particularly useful as energizers. If the developingagent employed were energized by ordinary alkalies the increasedclustering or coarseness of grain typical of prior art developers wouldresult.

Typical examples of the easilyoxidizable compounds according to thepresent invention are the alkali metal salts of compounds of theN-substituted o-amino phenols such as the alkali metal salts or2[di(hydroxyethyl) l-amino-i-hydroxy benzenes disclosed in U. 8. Patent1,712,716 of Gustav Reddelien and Werner Mueller. These salts arecharacterized by their sensitivity to oxidation and by the fact that,when so oxidized,

they set free a limited amount of alkali. These compounds have a weakdeveloping action by themselves but such developing action must beweaker than that of the developing a ent which the easily oxidizablecompound energizes. Thus,

5 when mono'N-methyl o-amino phenol is the de- 40 suits in an increasein speed without any appreciable increase in grain, It should be notedthat the improved results of the present invention as to fineness ofgrain with increased threshold speed, which are not achieved by the useof custl tomary sources of alkali, can be determined by measuring theiineness 0! grain on a graininess meter.

As the developing agent itself. we use mono N-alkyl o-amino phenols.Especially good resuits are obtained by the use of monomethyl orthoamino phenol. As a matter of fact. the addition of a substantial amountof hydroquinone to the ortho-methyl amino phenol is dssirablein order toobtain greatly improved contrast characteristics.Whilethcuseofhydroquinonehalblofl proposed previously in combinationwith orthomethyl amino-phenols. it has not been proposed in thethreefold combination or a mono-N-aikyl ortho amino phenol.hydroquinone, and an energizer oi the type described above. The newdevelopers which include these three ingredients are particularlyimportant because the extreme fineness of grain which is characteristicof the resulting developed image. This fineness of grain is achievedwithout loss in threshold speed. In fact, the threshold speed can evenbe increased by the use of larger amounts or the energizing compounds.

The following examples will serve to illustrate the invention. The partsare by weight unless otherwise indicated.

Examples Grams 1. Sodium suliite 100.0 o-Methyl aminophenol 5.0

2[Di(hydroxyethyl)] amino-l-hydroxy benzene sodium salt Hydroqulnone 7.5Water is added to make the solution up to 1000 cc. This solution willdevelop 35 mm. film of the type sold by the General Aniline & Film Co.under the trade name Supreme, in from 12-18 minutes at 68 F.

' Grams II. Sodium sulfite 100.0 o-Methyl amino phenol 5.0

zlDithydroxyethyhl amino 1 hydroxy benzene sodium salt Water is added tomake the solution up to 1000 cc. This solution will develop mm. film ofthe type mentioned in Example I, in from 20-30 minutes at 68 F.

Having now fully set forth and described my invention, and havingillustrated the best manner in which to perform it by specific examples.what I claim as new and desire to have secured by Letters Patent is:

l. A photographic developer comprising in combination an N-mono alkylo-amino phenol, and an alkali metal salt of a 2[di(hydroxyethyl)l-l-amino-l-hydroxy benzene which upon oxidation sets free limitedamounts of alkali said developer being initially free of alkali.

2. A photographic developer comprising in combination hydroquinone anN-mono alkyl 0- amino phenol, and an alkali metal salt of a 2 [di(hydroxyethyl) l -amino-1-hydron benzene which upon oxidation sets freelimited amounts of alkali said developer being initially free of alkali.

3. A. photographic developer comprising in combination hydroquinone,o-methyl aminophenol, and the sodium salt oi 2[di(hydroxyethyl)l-amino-l-hydroxy benzene which upon oxidation sets free limited amountsof alkali said developer being initially tree 0! alkali.

4. A photographic developer comprising in combination o-methylamino-phenol and the sodium salt of 2[di(hydroxyethylll-amino-1- hydroxybenzene which upon oxidation sets free limited amounts of alkali saiddeveloper being initially free of alkali.

vnannxnncmmrna.

CERTIFICATE OF COHRECTI ON.

parent No. 2,585,765.

September 25, 1915.

V'ERNE H RECIQ'EEYER.

It is hereby certified that error appears in patent requiringcorrectionas follows: Page 2, secof the above numbered the printed speclfication 0nd column, line 12., claim 1, for "-1-amino-1-" read -amino1-and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 26th day of February, A. D. 19li6.

iSeal) Leslie Frazer First Assistant Commissioner of Patents.

proposed previously in combination with orthomethyl amino-phenols. ithas not been proposed in the threefold combination or a mono-N-aikylortho amino phenol. hydroquinone, and an energizer oi the type describedabove. The new developers which include these three ingredients areparticularly important because the extreme fineness of grain which ischaracteristic of the resulting developed image. This fineness of grainis achieved without loss in threshold speed. In fact, the thresholdspeed can even be increased by the use of larger amounts or theenergizing compounds.

The following examples will serve to illustrate the invention. The partsare by weight unless otherwise indicated.

Examples Grams 1. Sodium suliite 100.0 o-Methyl aminophenol 5.0

2[Di(hydroxyethyl)] amino-l-hydroxy benzene sodium salt Hydroqulnone 7.5Water is added to make the solution up to 1000 cc. This solution willdevelop 35 mm. film of the type sold by the General Aniline & Film Co.under the trade name Supreme, in from 12-18 minutes at 68 F.

' Grams II. Sodium sulfite 100.0 o-Methyl amino phenol 5.0

zlDithydroxyethyhl amino 1 hydroxy benzene sodium salt Water is added tomake the solution up to 1000 cc. This solution will develop mm. film ofthe type mentioned in Example I, in from 20-30 minutes at 68 F.

Having now fully set forth and described my invention, and havingillustrated the best manner in which to perform it by specific examples.what I claim as new and desire to have secured by Letters Patent is:

l. A photographic developer comprising in combination an N-mono alkylo-amino phenol, and an alkali metal salt of a 2[di(hydroxyethyl)l-l-amino-l-hydroxy benzene which upon oxidation sets free limitedamounts of alkali said developer being initially free of alkali.

2. A photographic developer comprising in combination hydroquinone anN-mono alkyl 0- amino phenol, and an alkali metal salt of a 2 [di(hydroxyethyl) l -amino-1-hydron benzene which upon oxidation sets freelimited amounts of alkali said developer being initially free of alkali.

3. A. photographic developer comprising in combination hydroquinone,o-methyl aminophenol, and the sodium salt oi 2[di(hydroxyethyl)l-amino-l-hydroxy benzene which upon oxidation sets free limited amountsof alkali said developer being initially tree 0! alkali.

4. A photographic developer comprising in combination o-methylamino-phenol and the sodium salt of 2[di(hydroxyethylll-amino-1- hydroxybenzene which upon oxidation sets free limited amounts of alkali saiddeveloper being initially free of alkali.

vnannxnncmmrna.

CERTIFICATE OF COHRECTI ON.

parent No. 2,585,765.

September 25, 1915.

V'ERNE H RECIQ'EEYER.

It is hereby certified that error appears in patent requiringcorrectionas follows: Page 2, secof the above numbered the printed speclfication 0nd column, line 12., claim 1, for "-1-amino-1-" read -amino1-and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 26th day of February, A. D. 19li6.

iSeal) Leslie Frazer First Assistant Commissioner of Patents.

